Apparatus and method for locating the center of gravity of a golf club

ABSTRACT

An apparatus and method for supporting a golf club by the handle and rotating the club so that the head of the club spins about its center of gravity and marking the center of gravity of the club head to indicate the desired point of contact with a golf ball.

United States Patent [191 Finn [ Jan. 15, 1974- 1 APPARATUS AND METHOD FOR LOCATING THE CENTER or GRAVITY OF A GOLF CLUB [76] Inventor: Charles P. Finn, 406 Lamberton Dr,, Silver Spring, Md. 20902 22 Fi1ed: Aug. 4, 1972 21 App1.No.:277,970

[52] US. Cl. 73/65, 73/472 [51 Int. Cl. G01m 1/06 [58] Field of Search 73/65, 455, 456,

[56] References Cited UNITED STATES PATENTS 213,270 3/1879 Wiegand 73/472 X 2,608,856 9/1952 Van Degrift 73/472 87,940 3/1969 lves t 279/38 603,201 4/1898 Owens 269/157 X 1,490,109 4/1924 Hort 73/468 2,062,673 12/1936 Ogg et a1. 713/65 Primary Examiner-Charles A. Rueh] Attorney-A. Yates Dowel], Jr.

[57] ABSTRACT An apparatus and method for supporting a golf club by the handle and rotating the club so that the head of the club spins about its center of gravity and marking the center of gravity of the club head to indicate the desired point of contact with a golf ball.

4 Claims, 8 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to golf equipment and relates particularly to the apparatus and method of determining the center of gravity of a golf club.

2. Description of the Prior Art In the manufacture of golf clubs, care has been taken to provide sufficient weight in the head of a golf club so that the center of gravity is located within the head. In more expensive clubs, the head has been balanced about a fulcrum and some material has been removed or additional weights have been added so that the center of gravity has been located near the middle portion of the head. In less expensive clubs, little or no effort has been made to balance the club. Therefore, low handicap golfers normally purchase expensive matched clubs, while the occasional golfer may not feel that the investment in expensive clubs is worthwhile.

In substantially every club, there is what is known as the sweet spot which is the center of gravity of the mass of the club head at the point where the face of the club engages the ball. Striking the sweet spot generally results in a straight true flight of the ball for a distance commensurate with the force with which the ball is struck. The sweet spot can be readily discerned by a distinctive sound or thunk which does not occur when the ball is struck by any other portion of the club face. Since most golfers do not know the location of the center of gravity, they try to strike the ball with the cen' tral portion of the club face, even though the center of gravity or sweet spot may be located as much as an inch away from the center ofthe face. The more expensive clubs attempt to locate the center of gravity at the center of the face of the club; however, this has not always been satisfactory since the results have varied from club to club. Some examples of prior art are the patent to Ogg et al. US. Pat. No. 2,062,673 which discloses a fulcrum type balancing apparatus for a golf club, and the French patent No. 707,529 which discloses a complicated apparatus for rotating a ski pole along its longitudinal axis to determine the center of gravity thereof.

SUMMARY OF THE INVENTION The present invention is an apparatus and method of locating and marking the center of gravity or sweet spot of a golf club by clamping one end of the shaft with a device permitting free eccentric rotation or rotation about a non-fixed axis and rotating the club so that the golf club head spins about its center of gravity. When the exact center of gravity has been determined, a substantially permanent mark is applied to either the face of the club or to the top surface, not only to mark the center of gravity, but also to serve as a constant reference point indicating the desirable position where the face of the club should engage the ball.

It is an object of the invention to provide an apparatus to clampingly engage the end ofa golf club shaft re mote from the head and such apparatus is connected to a rotation imparting device by means of a universal connection or flexible shaft so that the golf club head will rotate about its center of gravity.

Another object of the invention is to provide a relatively simple method of determining the center of gravity of a golf club so that both professional and amateur golfers can determine the best location on a golf club in which the club should engage the ball.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation illustrating one application of the present invention.

FIG. 2 is a side elevation illustrating the apparatus in use.

FIG. 3 is an enlarged fragmentary section illustrating the clamping apparatus.

FIG. 4 is a front elevation of a golf club head with a temporary marker applied thereto.

FIG. 5 is a section on the line 55 of FIG. 4.

FIG. 6 is a front elevation of a golf club head illustrating a permanent marker applied after the center of gravity has been located.

FIG. 7 is a section on the line 7-7 of FIG. 6.

FIG. 8 is a section similar to FIG. 3 of a modified form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With continued reference to the drawing, a golf club 10 is provided including a shaft 11 with a head 12 having a ball engaging face 13 located at one end of the shaft and a handle or gripping portion 14 at the oppositeiend of the shaft. The golf club 10 can be a wood for causing the ball to travel long distances, an iron used for approach shots to a green, or a putter used for rolling the ball into a cup. With each of the above men tioned clubs, it is desirable to know the location of the center of gravity so that the optimum point of contact between the ball and the club can be established, not only so that the ball will travel in a straight and true path during its flight, but also will achieve a distance commensurate with the force with which the ball is struck.

In order to determine the center of gravity or sweet spot of the club, a hinged yoke or clamp member 17 is provided having a pair of elongated generally semicylindrical body portions 18 connected together adjacent to one end by a pivot pin 19 to define a substantially hollow frusto-conical body. The pivot pin 19 is carried by a lug 20 projecting downwardly from one end of a conventional universal connection 21 and the opposite end of such universal connection is provided with an upwardly extending shank 22 adapted to be re ceived within a chuck 23 of a hand drill 24 or other rotation imparting apparatus such as a geared-down electric drill or the like. If desired, the universal connection could be replaced with a flexible shaft or other structure which permits rotation of the golf club about a non-fixed axis.

The opposite end of each of the body portions 18 is provided with a resilient bead 25 of rubber, elastomeric plastic, or the like for frictionally engaging the handle or gripping portion 14 of the club. With particular reference to FIG. 3, in order to tightly clamp the yoke 17 onto the handle 14, an adjusting device such as a screw 26 threadedly engages a nut 27 fixed to one of the body portions 18 and such screw has a head 28 at one end for rotating the screw 26 in either direction. The oppo site end of the screw 26 is provided. with a reduced portion 29 which extends through an opening 30 in the other body portion and such reduced portion has an enlargement 31 located exteriorly of the body portion 18.

Rotation of the screw 26 causes the body portions 18 to move toward or away from each other about the pivot 19 depending upon the direction of rotation of the screw 26.

With reference to FIG. 8, a modified form of yoke is provided in which a conventional screw 32 extends through aligned openings 33 in both body portions 18. The head 34 of the screw 32 engages one of the body portions, while a nut 35 mounted on the other body portion threadedly receives the screw 32. In this modification, rotation of the screw 32 in one direction draws the body portions 18 toward each other and a spring 36 or other resilient member is provided for urging the body portions apart when the screw 32 is rotated in the opposite direction.

After the yoke 17 has been clamped to the handle 14 of the golf club, the rotating apparatus 24 is operated preferably at a slow speed or speed such that the centrifugal action on the club is negligible so that the golf club rotates about the center of gravity of the head 12. While rotating the club, the operator of the device observes the approximate point of rotation of the club and halts rotation. Next, the operator applies a temporary mark, such as a paper or cloth ring or disk 37, to the face of the club by means of an adhesive or the like. Although the exact size and configuration of the temporary mark is unimportant, a conventional reinforcing ring for loose leaf binders has been found satisfactory. The temporary mark is attached at approximately the observed point of rotation. The club again is rotated by the rotating apparatus and the temporary mark 37 is observed. if the ring or disk 37 appears to remain in the same position and appears to be of the same size, then the ring or disk is located substantially at the center of gravity.

If the ring appears to be larger in size or appears to be elongated in either horizontal or vertical direction, rotation is halted and the position of the ring or disk is shifted approximately one-half the difference between the actual size of the ring and the apparent size of the ring during rotation. Thereafter the club is rotated again and the ring again is observed.

When the center of gravity has been determined, a substantially permanent mark or dot 38 is placed on the club face 13 to mark the center of gravity. The permanent dot 38 can be scratched on the face of the club, can be a dab of paint, or the like, or, as illustrated, the

dot can be a separate unit constructed of polyethylene film having a diameter of approximately one-eighth of an inch and a thickness of 2 or 3 mils which is attached to the club by a tenacious adhesive. When the temporary mark is a ring, as illustrated in FIG. 4, the permanent mark or dot can be applied to the face of the club through the open center of the ring before the ring is removed from the face of the club.

I claim:

1. A portable lightweight apparatus for locating the center of gravity of a golf club having an elongated shank with a gripping portion at one end and an offset head at the opposite end, comprising an elongated lightweight adjustable clamp having at least two portions disposed about a generally vertical axis, means for moving at least one of said portions toward the other portion to engage the gripping portion of the golf club along the axis of the shank, a flexible member connected to one end of said clamp, said flexible member including shank means located along the axis of said clamp and spaced therefrom, and rotating means having a chuck for receiving said handk means to that rotation of the flexible member rotates said clamp and causes the golf club carried by the clamp to rotate about the center of gravity thereof.

2. The structure of claim 1 in which said flexible member is a universal connection.

3. The structure of claim 1 including a resilient body mounted on the other end of said clamp in a position to frictionally engage the gripping portion of the golf club.

4. The method of locating the center of gravity of the head of a golf club comprising the steps of; mounting a flexible connection on one end of said golf club, rotating said flexible connection to cause said club to rotate about the center of gravity of the head while observing the approximate center of gravity, halting rotation of said club and applying a temporary mark to the head at approximately the observed center of gravity, rotating the club again while observing the temporary mark, shifting the temporary mark if necessary until the mark maintains its normal appearance during rotation, and applying a permanent mark to the head of the club in place of the temporary mark after the center of gravity has been determined. 

1. A portable lightweight apparatus for locating the center of gravity of a golf club having an elongated shank with a gripping portion at one end and an offset head at the opposite end, comprising an elongated lightweight adjustable clamp having at least two portions disposed about a generally vertical axis, means for moving at least one of said portions toward the other portion to engage the gripping portion of the golf club along the axis of the shank, a flexible member connected to one end of said clamp, said flexible member including shank means located along the axis of said clamp and spaced therefrom, and rotating means having a chuck for receiving said handk means to that rotation of the flexible member rotates said clamp and causes the golf club carried by the clamp to rotate about the center of gravity thereof.
 2. The structure of claim 1 in which said flexible member is a universal connection.
 3. The structure of claim 1 including a resilient body mounted on the other end of said clamp in a position to frictionally engage the gripping portion of the golf club.
 4. The method of locating the center of gravity of the head of a golf club comprising the steps of; mounting a flexible connection on one end of said golf club, rotating said flexible connection to cause said club to rotate about the center of gravity of the head while observing the approximate center of gravity, halting rotation of said club and applying a temporary mark to the head at approximately the observed center of gravity, rotating the club again while observing the temporary mark, shifting the temporary mark if necessary Until the mark maintains its normal appearance during rotation, and applying a permanent mark to the head of the club in place of the temporary mark after the center of gravity has been determined. 